A tensioning device is provided for tensioning the metal strap of a metal wall structure. The tensioning device includes an elongated bar having a handle and a pair of jaws where one jaw is secured to the elongated bar and another jaw projects from the handle. The jaws are operatively connected between the metal strap and the wall structure. In particular, one jaw is operatively connected or anchored to the wall structure and the other jaw is connected to the metal strap. The handle includes a trigger mechanism for moving the jaws with respect to each other. By actuating the trigger mechanism and closing the jaws, the metal strap is tensioned. After the metal strap is tensioned, it is securely fastened to the wall structure.